I do think carb needs are a function of activity level (and probably other factors too). Although I personally have known athletes on moderately low-carb diets.

Part of the issue is the definition of low-carb. Even Atkins (the diet most often accused of being too low carb) adds carbs and slowly increases them until a healthy weight is maintained. Atkins never gives an upper limit on carbs - you just gradually increase until you stop losing. Then you cut back until you reach a healthy weight, and you eat as many carbs as allows you to maintain the healthy weight.

There is no universal definition of low-carb. Diets as high as 200g per day or as high as 65% of calories from carbs have been described and considered "low-carb," by various experts in the field of dietetics and nutrition. To a large degree, "low" is in the eye of the beholder.

What is interesting is that as the national average for weight has increased, so has carb levels (and protein levels have been declining).

I recently read an article about the "fattest cities" and read that in some of these areas the average carb intake was as high as 90% of calories, with protein levels being negiligible in some cases (especially where poverty was a significant contributing factor).

I too thrive on a lower carb diet. I eat beans, legumes and things of that nature, and I have been known to eat sweet potatoes and squash, but ultimately, I'm not a large consumer of other types of carbs. In my diet, nothing is off limits, but I have found that when I eat a lower carb, I am fuller longer, feel the most energetic and don't feel the need to eat a bunch of sugar. Now, some people do better with more carbs, and I am nobody to argue that. But I will agree with Kaplods. Nobody can even say one size fits all when it comes to diet.